Bidirectional DC-DC conversion circuit, electric equipment and energy storage system

Abstract

The utility model discloses a bidirectional DC-DC conversion circuit, electric equipment and an energy storage system. The bidirectional DC-DC conversion circuit comprises a control module, an energy storage module, a first switching device, a second switching device, a first impedance module, a third switching device, a fourth switching device, an output capacitor and a second impedance module. The control module responds to the situation that the input and output voltage difference is smaller than a first voltage difference threshold value and controls the first switching device, the second switching device, the third switching device and the fourth switching device to be switched on, and when the voltage of the energy storage module is larger than that of the output capacitor, the energy storage module discharges to the output capacitor; and when the voltage of the energy storage module is smaller than that of the output capacitor, the energy storage module is charged by the output capacitor. Through the mode, the switching time delay is reduced, the response delay is reduced, and the switching efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of direct current-direct current conversion, in particular to a bidirectional direct current-direct current conversion circuit, an electrical equipment and an energy storage system. BACKGROUND

[0002] It is known that, as high-frequency small-size power is large, the peak load of the load equipment is large, and the output voltage drops and the input grid harmonics are large when the load jumps. The current common methods are: 1) increasing the capacitance at the output end, and increasing the loop response characteristic at the same time, 2) increasing the input harmonic filter. In order to cope with the above situation, the common practice on the market is to increase an online direct current-direct current converter and an energy storage filter at the output bus line, when the output load is light, the direct current-direct current converter works in the PWM charging mode to charge the energy storage filter, when the load is heavy, the direct current-direct current converter works in the PWM discharging mode to discharge the energy storage filter, but there is a time delay in the switching process and a converter response delay in this PWM charging and discharging. CONTENT OF THE INVENTION

[0003] The present application provides a bidirectional direct current-direct current conversion circuit, an electrical equipment and an energy storage system, which can reduce the switching time delay and the response delay, and improve the switching efficiency.

[0004] In a first aspect, the present application provides a bidirectional DC-DC conversion circuit, comprising: a control module; an energy storage module; a first switching device, a first end of the first switching device being coupled to a first end of the energy storage module, a control end of the first switching device being coupled to the control module; a second switching device, a first end of the second switching device being coupled to a second end of the first switching device, a control end of the second switching device being coupled to the control module; a first impedance module, a first end of the first impedance module being coupled to the second end of the first switching device; a third switching device, a first end of the third switching device being coupled to a second end of the first impedance module, a control end of the third switching device being coupled to the control module; a fourth switching device, a first end of the fourth switching device being coupled to the first end of the third switching device, a control end of the fourth switching device being coupled to the control module; an output capacitor, a first end of the output capacitor being coupled to a second end of the third switching device; a second impedance module, a first end of the second impedance module being coupled to a second end of the second switching device, a second end of the second impedance module being coupled to a second end of the energy storage module, a third end of the second impedance module being coupled to a second end of the fourth switching device, a fourth end of the second impedance module being coupled to a second end of the output capacitor; wherein an impedance of the first impedance module is greater than an impedance of the second impedance module; wherein the control module controls the first switching device, the second switching device, the third switching device and the fourth switching device to be conductive in response to an input-output voltage difference being less than a first voltage difference threshold value, when a voltage of the energy storage module is greater than a voltage of the output capacitor, a current flows from the first end of the second impedance module to the third end of the second impedance module, and the energy storage module discharges to the output capacitor; when the voltage of the energy storage module is less than the voltage of the output capacitor, a current flows from the third end of the second impedance module to the first end of the second impedance module, and the output capacitor charges to the energy storage module.

[0005] wherein, during the discharging process of the energy storage module to the output capacitor, the control module controls the first switching device to be non-conductive in response to a discharging current being greater than a first discharging current threshold value, and a current flows from the second end of the second impedance module to the third end of the second impedance module.

[0006] wherein, during the discharging process of the energy storage module to the output capacitor, the control module controls the first switching device to be conductive in response to a discharging current being less than a second discharging current threshold value; wherein the second discharging current threshold value is less than the first discharging current threshold value.

[0007] wherein, during the charging process of the output capacitor to the energy storage module, the control module controls the third switching device to be non-conductive in response to a charging current being greater than a first charging current threshold value, and a current flows from the fourth end of the second impedance module to the first end of the second impedance module.

[0008] wherein, during the charging process of the output capacitor to the energy storage module, the control module controls the third switching device to be conductive in response to a charging current being less than a second charging current threshold value; wherein the second charging current threshold value is less than the first charging current threshold value.

[0009] The control module controls the first switch device and the third switch device to be turned on, the second switch device and the fourth switch device to be turned off, and the first impedance module to be connected to the charge-discharge circuit in response to the input-output voltage difference being greater than the first voltage difference threshold.

[0010] The second impedance module comprises: a first impedance unit, a first end of the first impedance unit being coupled to a second end of the second switch device, and a second end of the first impedance unit being coupled to a second end of the fourth switch device; a first diode, a cathode of the first diode being coupled to the first end of the first impedance unit, and an anode of the first diode being coupled to the second end of the energy storage module; and a second diode, a cathode of the second diode being coupled to the second end of the first impedance unit, and an anode of the second diode being coupled to a second end of the output capacitor.

[0011] The second impedance module comprises: a first impedance unit, a first end of the first impedance unit being coupled to a second end of the second switch device, and a second end of the first impedance unit being coupled to a second end of the fourth switch device; a fifth switch device, a first end of the fifth switch device being coupled to the first end of the first impedance unit, a second end of the fifth switch device being coupled to the second end of the energy storage module, and a control end of the fifth switch device being coupled to the control module; and a sixth switch device, a first end of the sixth switch device being coupled to the second end of the first impedance unit, a second end of the sixth switch device being coupled to the second end of the output capacitor, and a control end of the sixth switch device being coupled to the control module.

[0012] In a second aspect, the present application provides a power utilization device comprising the bidirectional DC-DC conversion circuit as provided in the first aspect.

[0013] In a third aspect, the present application provides an energy storage system comprising the bidirectional DC-DC conversion circuit as provided in the first aspect.

[0014] The bidirectional DC-DC conversion circuit, the power utilization device and the energy storage system provided in the present application have the following beneficial effects: Different from the prior art, the second impedance module is added in the bidirectional DC-DC conversion circuit, and the impedance of the second impedance module is smaller than that of the first impedance module. Therefore, when the input-output voltage difference is smaller than the first voltage difference threshold, and the first switch device, the second switch device, the third switch device and the fourth switch device are turned on, the seamless switching of charge-discharge and the automatic realization of the discharge from the energy storage module to the output capacitor and the charge-discharge from the output capacitor to the energy storage module can be realized according to the voltage relationship between the energy storage module and the output capacitor, so as to reduce the switching time delay and the response delay, and improve the switching efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments description will be briefly introduced. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor. Among them:

[0016] Figure 1 is a structural schematic diagram of an embodiment of the bidirectional DC-DC conversion circuit provided by the present application;

[0017] Figure 2 is a current flow direction schematic diagram of an application scenario of the bidirectional DC-DC conversion circuit provided by the present application;

[0018] Figure 3 is a current flow direction schematic diagram of another application scenario of the bidirectional DC-DC conversion circuit provided by the present application;

[0019] Figure 4 is a current flow direction schematic diagram of another application scenario of the bidirectional DC-DC conversion circuit provided by the present application;

[0020] Figure 5 is a current flow direction schematic diagram of another application scenario of the bidirectional DC-DC conversion circuit provided by the present application;

[0021] Figure 6 is a structural schematic diagram of another embodiment of the bidirectional DC-DC conversion circuit provided by the present application;

[0022] Figure 7 is a current flow direction schematic diagram of another application scenario of the bidirectional DC-DC conversion circuit provided by the present application;

[0023] Figure 8 is a current flow direction schematic diagram of another application scenario of the bidirectional DC-DC conversion circuit provided by the present application;

[0024] Figure 9 is a current flow direction schematic diagram of another application scenario of the bidirectional DC-DC conversion circuit provided by the present application;

[0025] Figure 10 is a current flow direction schematic diagram of another application scenario of the bidirectional DC-DC conversion circuit provided by the present application;

[0026] Figure 11 is a structural schematic diagram of another embodiment of the bidirectional DC-DC conversion circuit provided by the present application;

[0027] Figure 12 is a current flow direction schematic diagram of another application scenario of the bidirectional DC-DC conversion circuit provided by the present application;

[0028] Figure 13 is a schematic diagram of current flow of another application scenario of the bidirectional DC-DC conversion circuit provided in the present application;

[0029] Figure 14 is a schematic diagram of current flow of another application scenario of the bidirectional DC-DC conversion circuit provided in the present application;

[0030] Figure 15 is a schematic diagram of current flow of another application scenario of the bidirectional DC-DC conversion circuit provided in the present application;

[0031] Figure 16 is a schematic diagram of waveforms of another application scenario of the bidirectional DC-DC conversion circuit provided in the present application;

[0032] Figure 17 is a schematic diagram of structure of an embodiment of the power utilization device provided in the present application;

[0033] Figure 18 is a schematic diagram of structure of an embodiment of the energy storage system provided in the present application. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. It can be understood that the specific embodiments described herein are only used to explain the present application, but not to limit the present application. In addition, it should be noted that, for the convenience of description, only the parts related to the present application are shown in the drawings, but not all the structures. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0035] Reference to“an embodiment” in this text means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. The phrase appears at various places in the specification intends to encompass the understanding that the particular embodiment described at that location is included in at least one embodiment of the present application. It is explicitly and implicitly understood that the embodiments described herein can be combined with other embodiments.

[0036] It is known that, with high frequency, small size power, large load equipment peak load, resulting in output voltage drop and input grid harmonics. The commonly used method is: 1) increase the output capacitor, while increasing the loop response characteristics, 2) increase the input harmonic. In order to deal with the above situation, the general practice on the market is to increase the online DC-DC converter and energy storage filter on the output bus line. When the output load is light, the DC-DC converter works in PWM charging mode to charge the energy storage filter. When the load is heavy, the DC-DC converter works in PWM discharge mode to discharge the energy storage filter. But this PWM charging and discharging has time delay and converter response delay in the switching process.

[0037] The disadvantages are: 1) the output is directly added with a capacitor, and the output capacitor and the bus are not decoupled. The loop speed is too fast, which can cause poor power stability. The harmonic compensator can cause high cost and volume.

[0038] 2) the output end increases the online DC-DC converter, and the PWM charging and discharging circuit causes switching time delay and converter response delay.

[0039] Based on this, the application proposes to add a second impedance module in the bidirectional DC-DC conversion circuit. The impedance of the second impedance module is smaller than that of the first impedance module. Therefore, when the input-output pressure difference is less than the first pressure difference threshold, and the first, second, third and fourth switch devices are turned on, the seamless switching of charging and discharging can be realized according to the voltage relationship between the energy storage module and the output capacitor, and the automatic discharge from the energy storage module to the output capacitor and the charging and discharging from the output capacitor to the energy storage module. In this way, switching time delay and response delay are reduced, switching efficiency is improved, and at least one of the above technical problems is solved. For details, see the following embodiments.

[0040] Reference Figure 1 , Figure 1 is a structural schematic diagram of an embodiment of the bidirectional DC-DC conversion circuit provided by the application. The bidirectional DC-DC conversion circuit 100 includes a control module (not shown in the figure), an energy storage module C1, a first switch device Q1, a second switch device Q2, a first impedance module Z1, a third switch device Q6, a fourth switch device Q5, an output capacitor C2 and a second impedance module Z2.

[0041] The first end of the first switch device Q1 is coupled to the first end of the energy storage module C1, and the control end of the first switch device Q1 is coupled to the control module.

[0042] The first end of the second switch device Q2 is coupled to the second end of the first switch device Q1, and the control end of the second switch device Q2 is coupled to the control module.

[0043] The first end of the first impedance module Z1 is coupled to the second end of the first switch Q1.

[0044] The first end of the third switch Q6 is coupled to the second end of the first impedance module Z1, and the control end of the third switch Q6 is coupled to the control module.

[0045] The first end of the fourth switch Q5 is coupled to the first end of the third switch Q6, and the control end of the fourth switch Q5 is coupled to the control module.

[0046] The first end of the output capacitor C2 is coupled to the second end of the third switch Q6.

[0047] The first end of the second impedance module Z2 is coupled to the second end of the second switch Q2, the second end of the second impedance module Z2 is coupled to the second end of the energy storage module C1, the third end of the second impedance module Z2 is coupled to the second end of the fourth switch Q5, and the fourth end of the second impedance module Z2 is coupled to the second end of the output capacitor C2; wherein the impedance of the first impedance module Z1 is greater than the impedance of the second impedance module Z2.

[0048] In some embodiments, the control module controls the first switch Q1, the second switch Q2, the third switch Q6 and the fourth switch Q5 to be turned on in response to the input-output voltage difference being less than the first voltage difference threshold. When the voltage of the energy storage module C1 is greater than the voltage of the output capacitor C2, the current flows from the first end of the second impedance module Z2 to the third end of the second impedance module Z2, and the energy storage module C1 discharges to the output capacitor C2.

[0049] Exemplarily, in combination with Figure 2 the description is as follows:

[0050] When the input-output voltage difference is less than the first voltage difference threshold, the first switch Q1, the second switch Q2, the third switch Q6 and the fourth switch Q5 are turned on (normally closed). The first impedance module Z1 is short-circuited by the second switch Q2 and the fourth switch Q5. Therefore, when the voltage of the energy storage module C1 is greater than the voltage of the output capacitor C2, the current flowing through the second impedance module Z2 increases, and the discharge current flows from the first end of the second impedance module Z2 to the third end of the second impedance module Z2, and the energy storage module C1 discharges to the output capacitor C2. The specific current direction is shown by the arrow direction in Figure 2 . That is, the current flows from the first end of the energy storage module C1 to the first switch Q1, the second switch Q2, the first end of the second impedance module Z2, the third end of the second impedance module Z2, the fourth switch Q5, the third switch Q6 and the first end of the output capacitor C2.

[0051] In some embodiments, in response to the input-output voltage differential being less than a first voltage differential threshold, the control module controls the first switching device Q1, the second switching device Q2, the third switching device Q6, and the fourth switching device Q5 to conduct. When the voltage of the energy storage module C1 is less than the voltage of the output capacitor C2, current flows from the third terminal of the second impedance module Z2 to the first terminal of the second impedance module Z2, and the output capacitor C2 charges the energy storage module C1.

[0052] For example, in combination Figure 3 To explain:

[0053] When the input-output voltage difference is less than the first voltage difference threshold, the first switch device Q1, the second switch device Q2, the third switch device Q6, and the fourth switch device Q5 are turned on (normally closed). The first impedance module Z1 is short-circuited by the second switch device Q2 and the fourth switch device Q5. Therefore, when the voltage of the energy storage module C1 is less than the voltage of the output capacitor C2, the current flowing through the second impedance module Z2 decreases, and the current flows from the third terminal of the second impedance module Z2 to the first terminal of the second impedance module Z2, and the output capacitor C2 charges the energy storage module C1. For specific current direction, please refer to Figure 3 The direction of the arrow in FIG. 1 is that the current flows from the first terminal of the output capacitor C2 to the third switch device Q6, the fourth switch device Q5, the third terminal of the second impedance module Z2, the first terminal of the second impedance module Z2, the second switch device Q2, the first switch device Q1, and the first terminal of the energy storage module C1.

[0054] In this embodiment, a second impedance module Z2 is added to the bidirectional DC-DC converter circuit 100. The impedance of the second impedance module Z2 is smaller than that of the first impedance module Z1. Therefore, when the input-output voltage difference is smaller than the first voltage difference threshold and the first switching device Q1, the second switching device Q2, the third switching device Q6, and the fourth switching device Q5 are controlled to be turned on, charging and discharging can be seamlessly switched based on the voltage relationship between the energy storage module C1 and the output capacitor C2. Discharge from the energy storage module C1 to the output capacitor C2 and charge and discharge from the output capacitor C2 to the energy storage module C1 can be automatically achieved. This reduces switching time delay and response delay, thereby improving switching efficiency.

[0055] In some embodiments, combined Figure 4 To illustrate: During the discharge process of the energy storage module C1 to the output capacitor C2, the control module controls the first switch device Q1 to be turned off in response to the discharge current being greater than the first discharge current threshold, and the current flows from the second end of the second impedance module Z2 to the third end of the second impedance module Z2. When the first switch device Q1 is turned off, the current flows from the second end of the second impedance module Z2 to the third end of the second impedance module Z2, and the current flowing through the second impedance module Z2 drops rapidly. For specific current direction, please refer to Figure 4the arrow direction in FIG. 6. That is, the flow direction of the current is from the second end of the energy storage module C1 to the second end of the second impedance module Z2, the third end of the second impedance module Z2, the fourth switch Q5, the third switch Q6, and the first end of the output capacitor C2.

[0056] In some embodiments, during the discharging of the energy storage module C1 to the output capacitor C2, the control module controls the first switch Q1 to be turned on in response to the discharging current being less than a second discharging current threshold. The second discharging current threshold is less than the first discharging current threshold. That is, after the first switch Q1 is controlled to be turned on, the discharging current increases, and the flow direction of the current is adjusted from Figure 4 the current direction of FIG. 6 to Figure 2 the current direction of FIG. 7.

[0057] In some embodiments, in combination with Figure 5 the following is explained: during the charging of the output capacitor C2 to the energy storage module C1, the control module controls the third switch Q6 to be turned off in response to the charging current being greater than a first charging current threshold. The current flows from the fourth end of the second impedance module Z2 to the first end of the second impedance module Z2. Specifically, the flow direction of the current is shown by the arrow direction in FIG. 8. That is, the flow direction of the current is from the second end of the output capacitor C2 to the fourth end of the second impedance module Z2, the first end of the second impedance module Z2, the second switch Q2, the first switch Q1, and the first end of the energy storage module C1. Figure 5

[0058] In some embodiments, during the charging of the output capacitor C2 to the energy storage module C1, the control module controls the third switch Q6 to be turned on in response to the charging current being less than a second charging current threshold. The second charging current threshold is less than the first charging current threshold. That is, after the third switch Q6 is controlled to be turned on, the charging current increases, and the flow direction of the current is adjusted from Figure 5 the current direction of FIG. 8 to Figure 3 the current direction of FIG. 9.

[0059] In some embodiments, the control module controls the first switch Q1 and the third switch Q6 to be turned on, and the second switch Q2 and the fourth switch Q5 to be turned off in response to the input-output voltage difference being greater than a first voltage difference threshold. The first impedance module Z1 is connected to the charging and discharging circuit. That is, at this time, the second impedance module Z2 does not participate in the work, and the bidirectional DC-DC conversion circuit 100 enters the PWM mode.

[0060] Referring to Figure 6 , Figure 6 ​is a structural schematic diagram of another embodiment of the bidirectional DC-DC conversion circuit 100 provided by the present application. The bidirectional DC-DC conversion circuit 100 comprises a control module, an energy storage module C1, a first switching device Q1, a second switching device Q2, a first impedance module Z1, a third switching device Q6, a fourth switching device Q5, an output capacitor C2 and a second impedance module Z2.

[0061] The second impedance module Z2 comprises a first impedance unit L1, a first diode D1 and a second diode D2.

[0062] The first end of the first impedance unit L1 is coupled to the second end of the second switching device Q2, and the second end of the first impedance unit L1 is coupled to the second end of the fourth switching device Q5.

[0063] The cathode of the first diode D1 is coupled to the first end of the first impedance unit L1, and the anode of the first diode D1 is coupled to the second end of the energy storage module C1.

[0064] The cathode of the second diode D2 is coupled to the second end of the first impedance unit L1, and the anode of the second diode D2 is coupled to the second end of the output capacitor C2.

[0065] In some embodiments, the control module controls the first switching device Q1, the second switching device Q2, the third switching device Q6 and the fourth switching device Q5 to be turned on in response to the input-output voltage difference being less than the first voltage difference threshold. When the voltage of the energy storage module C1 is greater than the voltage of the output capacitor C2, the current flows from the first end of the first impedance unit L1 to the second end of the first impedance unit L1, and the energy storage module C1 discharges to the output capacitor C2.

[0066] Exemplarily, the bidirectional DC-DC conversion circuit 100 provided by the present application is described in combination with Figure 7 as follows:

[0067] When the input-output voltage difference is less than the first voltage difference threshold, the first switching device Q1, the second switching device Q2, the third switching device Q6 and the fourth switching device Q5 are turned on (normally closed). The first impedance module Z1 is short-circuited by the second switching device Q2 and the fourth switching device Q5. Therefore, when the voltage of the energy storage module C1 is greater than the voltage of the output capacitor C2, the current flowing through the first impedance unit L1 increases, and the discharge current flows from the first end of the first impedance unit L1 to the second end of the first impedance unit L1, the fourth switching device Q5, the third switching device Q6 and the first end of the output capacitor C2, and the energy storage module C1 discharges to the output capacitor C2. The specific current direction is shown by the arrow direction in Figure 7 . That is, the current flows from the first end of the energy storage module C1 to the first switching device Q1, the second switching device Q2, the first end of the first impedance unit L1, the second end of the first impedance unit L1, the fourth switching device Q5, the third switching device Q6 and the first end of the output capacitor C2.

[0068] In some embodiments, the control module controls the first switch Q1, the second switch Q2, the third switch Q6 and the fourth switch Q5 to be turned on in response to the input-output voltage difference being less than the first voltage difference threshold. When the voltage of the energy storage module C1 is less than the voltage of the output capacitor C2, the current flows from the second end of the first impedance unit L1 to the first end of the first impedance unit L1, and the output capacitor C2 charges the energy storage module C1.

[0069] Exemplarily, the control module controls the first switch Q1, the second switch Q2, the third switch Q6 and the fourth switch Q5 to be turned on in response to the input-output voltage difference being less than the first voltage difference threshold. Figure 8 Exemplarily, the control module controls the first switch Q1, the second switch Q2, the third switch Q6 and the fourth switch Q5 to be turned on in response to the input-output voltage difference being less than the first voltage difference threshold.

[0070] When the input-output voltage difference is less than the first voltage difference threshold, the first switch Q1, the second switch Q2, the third switch Q6 and the fourth switch Q5 are turned on (normally closed). The first impedance module Z1 is short-circuited by the second switch Q2 and the fourth switch Q5. Therefore, when the voltage of the energy storage module C1 is less than the voltage of the output capacitor C2, the current flowing through the first impedance unit L1 decreases, and the current flows from the second end of the first impedance unit L1 to the first end of the first impedance unit L1, the second switch Q2, the first switch Q1, and the output capacitor C2 charges the energy storage module C1. For the specific current direction, refer to the arrow direction in Figure 8 . That is, the current flows from the first end of the output capacitor C2 to the third switch Q6, the fourth switch Q5, the second end of the first impedance unit L1, the first end of the first impedance unit L1, the second switch Q2, the first switch Q1, and the first end of the energy storage module C1.

[0071] In this embodiment, a second impedance module Z2 is added to the bidirectional DC-DC conversion circuit 100, and the impedance of the second impedance module Z2 is less than that of the first impedance module Z1. Therefore, when the input-output voltage difference is less than the first voltage difference threshold and the first switch Q1, the second switch Q2, the third switch Q6 and the fourth switch Q5 are turned on, the charging and discharging can be seamlessly switched according to the voltage relationship between the energy storage module C1 and the output capacitor C2, and the discharging from the energy storage module C1 to the output capacitor C2 and the charging and discharging from the output capacitor C2 to the energy storage module C1 are automatically realized, thereby reducing the switching time delay and response delay and improving the switching efficiency.

[0072] In some embodiments, the control module controls the first switch Q1, the second switch Q2, the third switch Q6 and the fourth switch Q5 to be turned on in response to the input-output voltage difference being less than the first voltage difference threshold. Figure 9 Exemplarily, the control module controls the first switch Q1, the second switch Q2, the third switch Q6 and the fourth switch Q5 to be turned on in response to the input-output voltage difference being less than the first voltage difference threshold. Figure 9the arrow direction in FIG. 6. That is, the flow direction of the current is from the second end of the energy storage module C1 to the first diode D1, the first end of the first impedance unit L1, the second end of the first impedance unit L1, the fourth switch Q5, the third switch Q6, and the first end of the output capacitor C2.

[0073] In some embodiments, during the discharging of the energy storage module C1 to the output capacitor C2, the control module controls the first switch Q1 to be turned on in response to the discharging current being less than a second discharging current threshold. The second discharging current threshold is less than the first discharging current threshold. That is, after the first switch Q1 is controlled to be turned on, the discharging current increases, and the flow direction of the current is adjusted to be Figure 9 . Figure 7 .

[0074] In some embodiments, in combination with Figure 10 , it is explained that, during the charging of the output capacitor C2 to the energy storage module C1, the control module controls the third switch Q6 to be turned off in response to the charging current being greater than a first charging current threshold. The current flows from the second diode D2 to the first diode D1. When the third switch Q6 is turned off, the current flows from the second diode D2 and the first impedance unit L1 to the first diode D1. The flow direction of the current is shown by the arrow direction in FIG. 7. That is, the flow direction of the current is from the second end of the output capacitor C2 to the second diode D2, the second end of the first impedance unit L1, the first end of the first impedance unit L1, the second switch Q2, the first switch Q1, and the first end of the energy storage module C1. Figure 10

[0075] In some embodiments, during the charging of the output capacitor C2 to the energy storage module C1, the control module controls the third switch Q6 to be turned on in response to the charging current being less than a second charging current threshold. The second charging current threshold is less than the first charging current threshold. That is, after the third switch Q6 is controlled to be turned on, the charging current increases, and the flow direction of the current is adjusted to be Figure 10 . Figure 8 .

[0076] In some embodiments, the control module controls the first switch Q1 and the third switch Q6 to be turned on, the second switch Q2 and the fourth switch Q5 to be turned off, and the first impedance module Z1 to be connected to the charging and discharging circuit in response to the input-output voltage difference being greater than a first voltage difference threshold. That is, at this time, the second impedance module Z2 does not participate in the work, and the bidirectional DC-DC conversion circuit 100 enters the PWM mode.

[0077] Referring to Figure 11 , Figure 11 ​is a structural schematic diagram of another embodiment of the bidirectional DC-DC conversion circuit 100 provided by the present application. The bidirectional DC-DC conversion circuit 100 comprises a control module, an energy storage module C1, a first switching device Q1, a second switching device Q2, a first impedance module Z1, a third switching device Q6, a fourth switching device Q5, an output capacitor C2 and a second impedance module Z2.

[0078] The second impedance module Z2 comprises a first impedance unit L1, a fifth switching device Q3 and a sixth switching device Q4.

[0079] The first end of the first impedance unit L1 is coupled to the second end of the second switching device Q2, and the second end of the first impedance unit L1 is coupled to the second end of the fourth switching device Q5.

[0080] The first end of the fifth switching device Q3 is coupled to the first end of the first impedance unit L1, the second end of the fifth switching device Q3 is coupled to the second end of the energy storage module C1, and the control end of the fifth switching device Q3 is coupled to the control module.

[0081] The first end of the sixth switching device Q4 is coupled to the second end of the first impedance unit L1, the second end of the sixth switching device Q4 is coupled to the second end of the output capacitor C2, and the control end of the sixth switching device Q4 is coupled to the control module.

[0082] In some embodiments, in response to the input-output voltage difference being less than the first voltage difference threshold, the control module controls the first switching device Q1, the second switching device Q2, the third switching device Q6 and the fourth switching device Q5 to be turned on, and the fifth switching device Q3 and the sixth switching device Q4 to be turned off. When the voltage of the energy storage module C1 is greater than the voltage of the output capacitor C2, the current flows from the first end of the first impedance unit L1 to the second end of the first impedance unit L1, and the energy storage module C1 discharges to the output capacitor C2.

[0083] Exemplarily, in combination with Figure 12 the description is as follows:

[0084] When the input-output voltage difference is less than the first voltage difference threshold, the first switching device Q1, the second switching device Q2, the third switching device Q6 and the fourth switching device Q5 are turned on (normally closed). The fifth switching device Q3 and the sixth switching device Q4 are turned off. The first impedance module Z1 is short-circuited by the second switching device Q2 and the fourth switching device Q5. Therefore, when the voltage of the energy storage module C1 is greater than the voltage of the output capacitor C2, the current flowing through the first impedance unit L1 increases, and the discharge current flows from the first end of the first impedance unit L1 to the second end of the first impedance unit L1, the fourth switching device Q5 and the third switching device Q6, and the energy storage module C1 discharges to the output capacitor C2. The specific current direction is shown in Figure 12the arrow direction in FIG. 6. That is, the current flows from the first end of the energy storage module C1 to the first switch Q1, the second switch Q2, the first end of the first impedance unit L1, the second end of the first impedance unit L1, the fourth switch Q5, the third switch Q6, and the first end of the output capacitor C2.

[0085] In some embodiments, in response to the input-output voltage difference being less than the first voltage difference threshold, the control module controls the first switch Q1, the second switch Q2, the third switch Q6, and the fourth switch Q5 to be turned on, and the fifth switch Q3 and the sixth switch Q4 to be turned off. When the voltage of the energy storage module C1 is less than the voltage of the output capacitor C2, the current flows from the second end of the first impedance unit L1 to the first end of the first impedance unit L1, and the output capacitor C2 charges the energy storage module C1.

[0086] Exemplarily, in combination with Figure 13 The following is described:

[0087] When the input-output voltage difference is less than the first voltage difference threshold, the first switch Q1, the second switch Q2, the third switch Q6, and the fourth switch Q5 are turned on (normally closed). The fifth switch Q3 and the sixth switch Q4 are turned off. The first impedance module Z1 is short-circuited by the second switch Q2 and the fourth switch Q5. Therefore, when the voltage of the energy storage module C1 is less than the voltage of the output capacitor C2, the current flowing through the first impedance unit L1 decreases, and the current flows from the second end of the first impedance unit L1 to the first end of the first impedance unit L1, the second switch Q2, the first switch Q1, and the output capacitor C2 charges the energy storage module C1. Specifically, the current direction is shown by the arrow direction in FIG. 6. That is, the current flows from the first end of the energy storage module C1 to the first switch Q1, the second switch Q2, the first end of the first impedance unit L1, the second end of the first impedance unit L1, the fourth switch Q5, the third switch Q6, and the first end of the output capacitor C2. Figure 13

[0088] In this embodiment, the second impedance module Z2 is added to the bidirectional DC-DC conversion circuit 100, and the impedance of the second impedance module Z2 is less than that of the first impedance module Z1. Therefore, when the input-output voltage difference is less than the first voltage difference threshold and the first switch Q1, the second switch Q2, the third switch Q6, and the fourth switch Q5 are turned on, the seamless switching of charging and discharging can be realized according to the voltage relationship between the energy storage module C1 and the output capacitor C2, and the automatic realization of discharging from the energy storage module C1 to the output capacitor C2 and charging and discharging from the output capacitor C2 to the energy storage module C1, so as to reduce the switching time delay and the response delay, and improve the switching efficiency.

[0089] In some embodiments, in combination with Figure 14 ​It is explained that during the discharging process of the energy storage module C1 to the output capacitor C2, the control module controls the first switch device Q1 to be off and the fifth switch device Q3 to be on in response to the discharging current being greater than the first discharging current threshold. The current flows from the fifth switch device Q3 to the second end of the first impedance unit L1. When the first switch device Q1 is off and the fifth switch device Q3 is on, the current flows from the fifth switch device Q3 to the second end of the first impedance unit L1. The current flowing through the first impedance unit L1 decreases rapidly. For the current direction, refer to the arrow direction in Figure 14 . That is, the current flows from the second end of the energy storage module C1 to the fifth switch device Q3, the first end of the first impedance unit L1, the second end of the first impedance unit L1, the fourth switch device Q5, the third switch device Q6, and the first end of the output capacitor C2.

[0090] In some embodiments, during the discharging process of the energy storage module C1 to the output capacitor C2, the control module controls the first switch device Q1 to be on and the fifth switch device Q3 to be off in response to the discharging current being less than the second discharging current threshold. The second discharging current threshold is less than the first discharging current threshold. That is, after the first switch device Q1 is controlled to be on, the discharging current increases, and the current direction is adjusted from Figure 14 to Figure 12 .

[0091] In some embodiments, in combination with Figure 15 It is explained that during the charging process of the output capacitor C2 to the energy storage module C1, the control module controls the third switch device Q6 to be off and the sixth switch device Q4 to be on in response to the charging current being greater than the first charging current threshold. The current flows from the sixth switch device Q4 to the first switch device Q1. When the third switch device Q6 is off, the current flows from the sixth switch device Q4 and the first impedance unit L1 to the first switch device Q1. For the current direction, refer to the arrow direction in Figure 15 . That is, the current flows from the second end of the output capacitor C2 to the sixth switch device Q4, the second end of the first impedance unit L1, the first end of the first impedance unit L1, the second switch device Q2, the first switch device Q1, and the first end of the energy storage module C1.

[0092] In some embodiments, during the charging process of the output capacitor C2 to the energy storage module C1, the control module controls the third switch device Q6 to be on in response to the charging current being less than the second charging current threshold. The second charging current threshold is less than the first charging current threshold. That is, after the third switch device Q6 is controlled to be on, the charging current increases, and the current direction is adjusted from Figure 15 to Figure 13 .

[0093] In some embodiments, the control module controls the first switch Q1 and the third switch Q6 to be turned on, the second switch Q2 and the fourth switch Q5 to be turned off, and the first impedance module Z1 to be connected to the charge-discharge circuit in response to the input-output pressure difference being greater than the first pressure difference threshold. That is, at this time, the second impedance module Z2 does not participate in the work, and the bidirectional DC-DC conversion circuit 100 enters the PWM mode.

[0094] In the present application, the first switch Q1, the second switch Q2, the third switch Q6, the fourth switch Q5, the fifth switch Q3, and the sixth switch Q4 in any of the above embodiments can be any type of transistor such as a MOS tube or an IGBT tube. In some embodiments, the first switch Q1, the second switch Q2, the third switch Q6, the fourth switch Q5, the fifth switch Q3, and the sixth switch Q4 also have a body diode built-in. Compared with a diode, a transistor has lower loss.

[0095] Referring to Figure 16 When the output current is impacted between 0-100A, the bidirectional DC-DC conversion circuit 100 naturally switches between charging and discharging, with positive and negative 50A, wherein, Figure 16 V2 in the above formula represents the voltage of the output capacitor C2, I(R6) represents the current of the load device, and I(L1) represents the current of the first impedance unit L1. The bidirectional DC-DC conversion circuit 100 of the present application belongs to an auxiliary circuit for assisting an AC-DC circuit, that is, the output capacitor C2 is also coupled to the AC-DC circuit. When the load device changes, it seamlessly switches to assist the AC-DC circuit to charge and discharge, reduces input harmonics and pollution to the power grid, and reduces output voltage drop and overshoot, and is more suitable for large dynamic loads.

[0096] Referring to Figure 17 , Figure 17 is a structural schematic diagram of an embodiment of a power consumption device provided by the present application. The power consumption device includes a bidirectional DC-DC conversion circuit 100.

[0097] Referring to Figure 18 , Figure 18 is a structural schematic diagram of an embodiment of a power consumption device provided by the present application. The power consumption device includes a bidirectional DC-DC conversion circuit 100.

[0098] In summary, the bidirectional DC-DC conversion circuit 100, the electric device and the energy storage system provided by the application, the second impedance module Z2 is added in the bidirectional DC-DC conversion circuit 100, the impedance of the second impedance module Z2 is smaller than that of the first impedance module Z1, therefore, when the input-output voltage difference is smaller than the first voltage difference threshold, and the first switch device Q1, the second switch device Q2, the third switch device Q6 and the fourth switch device Q5 are turned on, the seamless switching of charging and discharging can be realized according to the voltage relationship between the energy storage module C1 and the output capacitor C2, the discharging of the energy storage module C1 to the output capacitor C2 and the charging and discharging of the output capacitor C2 to the energy storage module C1 are automatically realized, so as to reduce the switching time delay and the response delay, and improve the switching efficiency.

[0099] In several embodiments provided in the application, it should be understood that the disclosed methods and devices can be implemented in other ways. For example, the device embodiments described above are only illustrative, for example, the division of the modules or units is only a logical function division, and actual implementation can have another division mode, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0100] The integrated units in the above other embodiments, if realized in the form of software function units and sold or used as independent products, can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the application essentially or the parts that make contributions to the prior art or the whole or part of the technical solutions can be embodied in the form of software products, the computer software products are stored in a storage medium, and include a plurality of instructions for making a computer device (which can be a personal computer, a server, or a network device, etc.) or a processor 10 execute all or part of the steps of the methods described in the embodiments of the application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk and various program code storage media.

[0101] The above description is only the embodiment of the application, and does not limit the patent scope of the application, and any equivalent structure or equivalent process transformation based on the content of the specification and the drawings, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the application.

Claims

1. A bidirectional DC-DC conversion circuit, characterized in that: The bidirectional DC-DC conversion circuit comprises: Control module; Energy storage module; a first switching device, wherein a first end of the first switching device is coupled to a first end of the energy storage module, and a control end of the first switching device is coupled to the control module; a second switch device, wherein a first terminal of the second switch device is coupled to the second terminal of the first switch device, and a control terminal of the second switch device is coupled to the control module; a first impedance module, wherein a first end of the first impedance module is coupled to the second end of the first switching device; a third switching device, wherein a first terminal of the third switching device is coupled to the second terminal of the first impedance module, and a control terminal of the third switching device is coupled to the control module; a fourth switch device, wherein a first terminal of the fourth switch device is coupled to the first terminal of the third switch device, and a control terminal of the fourth switch device is coupled to the control module; an output capacitor, a first terminal of the output capacitor being coupled to the second terminal of the third switching device; a second impedance module, wherein a first end of the second impedance module is coupled to the second end of the second switch device, a second end of the second impedance module is coupled to the second end of the energy storage module, a third end of the second impedance module is coupled to the second end of the fourth switch device, and a fourth end of the second impedance module is coupled to the second end of the output capacitor; wherein the impedance of the first impedance module is greater than the impedance of the second impedance module; In which, in response to the input-output voltage difference being less than a first voltage difference threshold, the control module controls the first switching device, the second switching device, the third switching device, and the fourth switching device to be turned on; when the voltage of the energy storage module is greater than the voltage of the output capacitor, current flows from the first end of the second impedance module to the third end of the second impedance module, and the energy storage module discharges to the output capacitor; when the voltage of the energy storage module is less than the voltage of the output capacitor, current flows from the third end of the second impedance module to the first end of the second impedance module, and the output capacitor charges the energy storage module.

2. The bidirectional DC-DC conversion circuit according to claim 1, wherein: During the process of the energy storage module discharging to the output capacitor, the control module controls the first switching device to be turned off in response to the discharge current being greater than the first discharge current threshold, and the current flows from the second end of the second impedance module to the third end of the second impedance module.

3. The bidirectional DC-DC conversion circuit according to claim 2, wherein: During the process of the energy storage module discharging to the output capacitor, the control module controls the first switching device to turn on in response to the discharge current being less than a second discharge current threshold; wherein the second discharge current threshold is less than the first discharge current threshold.

4. The bidirectional DC-DC conversion circuit according to claim 1, wherein: During the process of the output capacitor charging the energy storage module, the control module controls the third switch device to be turned off in response to the charging current being greater than the first charging current threshold, and the current flows from the fourth end of the second impedance module to the first end of the second impedance module.

5. The bidirectional DC-DC conversion circuit according to claim 4, characterized in that: During the process of the output capacitor charging the energy storage module, the control module controls the third switching device to turn on in response to the charging current being less than a second charging current threshold; wherein the second charging current threshold is less than the first charging current threshold.

6. The bidirectional DC-DC conversion circuit according to claim 1, characterized in that: In response to the input-output voltage difference being greater than the first voltage difference threshold, the control module controls the first switching device and the third switching device to be turned on, the second switching device and the fourth switching device to be turned off, and the first impedance module to be connected to the charge and discharge circuit.

7. The bidirectional DC-DC conversion circuit according to claim 1, wherein: The second impedance module includes: a first impedance unit, wherein a first end of the first impedance unit is coupled to the second end of the second switching device, and a second end of the first impedance unit is coupled to the second end of the fourth switching device; a first diode, wherein a cathode of the first diode is coupled to the first end of the first impedance unit, and an anode of the first diode is coupled to the second end of the energy storage module; A second diode, wherein a cathode of the second diode is coupled to the second end of the first impedance unit, and an anode of the second diode is coupled to the second end of the output capacitor.

8. The bidirectional DC-DC conversion circuit according to claim 1, wherein: The second impedance module includes: a first impedance unit, wherein a first end of the first impedance unit is coupled to the second end of the second switching device, and a second end of the first impedance unit is coupled to the second end of the fourth switching device; a fifth switching device, wherein a first end of the fifth switching device is coupled to the first end of the first impedance unit, a second end of the fifth switching device is coupled to the second end of the energy storage module, and a control end of the fifth switching device is coupled to the control module; A sixth switching device, wherein a first end of the sixth switching device is coupled to the second end of the first impedance unit, a second end of the sixth switching device is coupled to the second end of the output capacitor, and a control end of the sixth switching device is coupled to the control module.

9. An electrical device, characterized in that: The invention comprises the bidirectional DC-DC conversion circuit according to any one of claims 1 to 8.

10. An energy storage system, characterized in that: The invention comprises the bidirectional DC-DC conversion circuit according to any one of claims 1 to 8.

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